In a switching exchange, a register is a storage area that may comprise 64 sixteen-bit words for example; this storage area contains all the information inherent to setting up and clearing down calls; a register is addressed at the beginning of a call setting up phase or of a call clearing down phase and it is released at the end of said call handling phase.
A switching exchange includes several sets of registers. In any one set of registers, the registers are processed cyclically; thus, systems are known in which a register is processed during 125 microseconds once every 8 milliseconds and other systems are known in which a register is processed during 32 microseconds once every 16 milliseconds.
The main feature of such processing resides in the fact that the processing time for each register is independent from the load on the switching exchange. This feature is an advantage in heavy traffic, since it ensures regular processing of each register; it also facilitates signal timing operations; in contrast, it does not allow processing time to be optimized e.g. for setting up or clearing down a call, since the same time is assigned to free registers and to busy registers and, likewise all busy registers are assigned the same time regardless of whether they are processing slow events (monitoring time delays, the state of a loop, etc.) or fast events (e.g. dialling analysis).
Preferred embodiments of the present invention optimize fast event register processing times while maintaining cyclic processing of all the registers.